Studies of mammalian prion diseases such as bovine spongiform encephalopathy have suggested that different strains consist of prion proteins with different conformations. Two recent studies of yeast prions have now formally demonstrated that multiple stable protein conformations are the basis of strain variation. deposited research Transmissible spongiform encephalopathies (TSEs) are a group of closely related neurodegenerative conditions of animals | Minireview The mechanism of prion strain propagation Glenn C Telling Address Sanders Brown Center on Aging Department of Microbiology Immunology and Molecular Genetics Department of Neurology and PhD Program in Gerontology University of Kentucky Lexington KY 40536 USA. E-mail gtell2@ Published 22 April 2004 Genome Biology 2004 5 222 The electronic version of this article is the complete one and can be found online at http 2004 5 5 222 2004 BioMed Central Ltd Abstract Studies of mammalian prion diseases such as bovine spongiform encephalopathy have suggested that different strains consist of prion proteins with different conformations. Two recent studies of yeast prions have now formally demonstrated that multiple stable protein conformations are the basis of strain variation. Transmissible spongiform encephalopathies TSEs are a group of closely related neurodegenerative conditions of animals and humans that includes sheep scrapie chronic wasting disease of deer and elk bovine spongiform encephalopathy BSE and human Creutzfeldt-Jakob disease CJD . TSEs attracted interest and considerable controversy well before the epidemic of BSE and the subsequent appearance of a new variant of human CJD because of their extraordinary features. It was once widely believed that TSEs were caused by infectious agents containing a nucleic-acid genome but the prevailing view now attributes these diseases to subcellular pathogens called prions which are defined as small proteinaceous infectious particles that lack informational nucleic acid 1 . Although the precise molecular structure of the infectious agent has still not been definitively identified considerable evidence supports the unorthodox hypothesis that prions are composed largely if not entirely of a pathogenic conformation of the prion protein PrP referred to as PrPSc and that during the disease process PrPSc imposes its conformation on the normal host-encoded version of PrP PrPC resulting in the .
